Had replied by email, but don't see it here - I haven't disappeared!
Feedback appreciated and I've hunted around a bit more, too. Have been searching on the portlets mentioned, "PMO Accelerator" and related words. Either finding nothing except a reference to this thread, or long list (hundreds) of unspecific hits. An advanced search capability in DocOps would be appreciated.
Eventually found this: https://docops.ca.com/ca-ppm/15-1/en/add-ins-and-integrations/add-in-pmo-accelerator/additional-pmo-portlets
Putting "template" into IE Find box, clicking into each sublink, finally found a reference to how this template/methodology field works, including screenshot of Project Cycle Time Analysis portlet and some description of usage, which aligns with Samik's reply.
If this Template Type field affects anything else, will need to keep clicking through the pages... At least this puts me in a better place than when I started.
Appears from this documentation, the Project Cycle Time Analysis is a stand-alone portlet, not appearing on any pages - waiting to be added if/when we find a use for it (documentation doesn't say this - I'm deducing from it's location in this document under "Additional PMO Portlets" rather than in a chapter on PMO pages).
Problem wasn't lack of documentation - just very difficult to find.
Thanks for the feedback, it was helpful.